CORE SUMMARY/ABSTRACT The Molecular Pathology Core provides researchers in the Superfund Research Program with equipment and technical expertise necessary for the evaluation of molecular and morphological changes in cells, tissues, and organs following exposure to complex environmental contaminants. The Core houses state- of-the-art equipment, including an automated tissue processor, a paraffin embedding center, two automated microtomes, a cryostat, a vibratome for soft-tissue sectioning, a multiheaded light microscope with projection capabilities, a system for laser capture microdissection, and a slide scanner with analysis software for the identification and quantification of morphological structures. The Molecular Pathology Core is staffed by a director, a histologist and a histotechnician, who have expertise in histopathological and immunocytochemial methods, including fixation, dehydration, embedding, sectioning, histological staining, immunolabeling, high- resolution imaging, and quantitative image analysis. Facility staff provides all-inclusive services in sample preparation, offers assistance in imaging and image analysis and provides consultation for ongoing or future research projects. In addition, the core established an extensive training program for students and investigators who use the centrally available equipment. The broad, long-term objective of the Molecular Pathology Core is to contribute to the detection, diagnosis, and prevention of disease caused by exposures to complex environmental contaminants. This long- term goal will be achieved through the following specific aims: Specific Aim 1. Provide high-quality, cost- effective services in molecular pathology for the research projects in the Superfund Research Program. Specific Aim 2. Further integrate methodologies in the Molecular Pathology Core and the Leduc Bioimaging Facility, which houses electron, fluorescence, and confocal microscopes. Specific Aim 3. Identify the bottlenecks in specific protocols and design innovative solutions to improve the pipeline from the proposed experiments to publication of the results. Specific Aim 4. Provide training in tissue processing, sectioning, histological staining, immunolabeling, high-resolution imaging, and quantitative image analysis. The expected outcome from this work includes the identification of molecular markers and specific pathological changes in cell and tissue morphology following exposure to complex environmental contaminants. The results and the developed methodologies will be essential to the individual research projects in the Superfund Research Program and contribute to evidence-based risk assessment of environmental contaminants and mixtures. In addition, students who are trained in the Molecular Pathology Core will be equipped with interdisciplinary tools and approaches to tackle future problems in the environmental sciences.